Define what the coverlay contains
Qnity’s LF coverlay page identifies polyimide film coated with acrylic adhesive. Other selections require their own construction data. Record film and adhesive thickness separately in the proposed stack. The coverlay and flexible-mask comparison helps determine whether the feature pattern calls for a different protective process in part of the design.
Coverlay details to define
| Decision | Define | Review |
|---|---|---|
| Material | Film and adhesive grade | Compatibility with laminate and process |
| Openings | Finished exposed feature requirement | Registration and adhesive clearance |
| Boundary | Coverlay extent by region | Terminal and bend transition |
| Thickness | Film plus finished bondline assumptions | Mechanical and signal model |
Dimension openings around the real interface
Start from the pad, exposed terminal, or bond feature. Define what must remain accessible after registration variation and adhesive movement are considered. Do not assume the artwork opening equals the finished clear area. Ask for a review of fine pitch, isolated openings, and narrow cover bridges. Use the opening design guide to record those functional clearances.
Include coverlay in electrical and motion reviews
Protective layers add to local thickness and sit next to signal conductors. Include them in the stack and electrical model where relevant. Show where coverlay stops at a connector tail or transition. For movement qualification, use the actual film, adhesive, opening pattern, and process. A bare laminate strip does not exercise the same construction as the protected circuit you intend to release.
Before you release the design
- Show separate top and bottom coverlay patterns.
- Identify critical exposed contacts.
- Include coverlay in local stack totals.
- Agree inspection of functional opening clearances.
Watch points
- An adhesive intrusion into a contact area cannot be assessed from the film opening alone.
Practical questions
Should coverlay cover every part of the circuit?
Define coverage by function. Contacts and joining areas need intentional openings, and their boundaries should be part of the drawing.
Is coverlay thickness only the film?
No. Distinguish film thickness from the adhesive contribution and from the resulting finished local section.
Technical references
References support the material or design context. Check the exact grade, part number, document revision and project conditions before release.Updated 27 September 2026 · Technical content policy · Engineering guidance supports project review; the agreed drawing defines the build.